DOUBLE (from the Mid. Eng. duble, the form which gives the present pronunciation, through the Old Fr. duble, from Lat. duplus, twice as much), twice as much, or large, having two parts, having a part repeated, coupled, etc. The word appears as a substantive with the special meaning of the appearance to a person of his own apparition, generally regarded as a warning, or of such an apparition of one living person to another, the German Doppelgänger (see Apparitions). Another word often used with this meaning is "fetch." According to the New English Dictionary, "fetch" is chiefly of Irish usage, and may possibly be connected with "fetch," to bring or carry away, but it may be a separate word. The Corpus Glossary of the beginning of the 10th century seems to identify a word fæcce with mære, meaning a goblin which appears in "nightmare." "Double" is also used of a person whose resemblance to another is peculiarly striking or remarkable, so that confusion between them may easily arise.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)